/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * http://www.gnu.org/copyleft/gpl.html
 */

package com.l2dot.gameserver.util;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * extension loader for com.l2dot
 * @author galun
 * @version $Id: DynamicExtension.java,v 1.3 2006/05/14 17:19:39 galun Exp $
 */
public class DynamicExtension 
{
	private static Logger _log = Logger.getLogger(DynamicExtension.class.getCanonicalName());
	private JarClassLoader _classLoader;
	private static final String CONFIG = "config/extensions.ini";
	private Properties _prop;
	private ConcurrentHashMap<String, Object> _loadedExtensions;
	private static DynamicExtension _instance;
    private ConcurrentHashMap<String, ExtensionFunction> _getters;
    private ConcurrentHashMap<String, ExtensionFunction> _setters;

	/**
	 * create an instance of DynamicExtension
	 * this will be done by GameServer according to the altsettings.properties
	 *
	 */
	private DynamicExtension() 
	{
		if (_instance == null)
			_instance = this;
        _getters = new ConcurrentHashMap<String, ExtensionFunction>();
        _setters = new ConcurrentHashMap<String, ExtensionFunction>();
        initExtensions();
	}

    /**
     * get the singleton of DynamicInstance
     * @return the singleton instance
     */
    public static DynamicExtension getInstance() 
    {
        if (_instance == null)
            _instance = new DynamicExtension();
        return _instance;
    }

    /**
     * get an extension object by class name
     * @param className he class name as defined in the extension properties
     * @return the object or null if not found
     */
    public Object getExtension(String className) 
    {
        return _loadedExtensions.get(className);
    }

	/**
	 * initialize all configured extensions
	 *
	 */
	public String initExtensions() 
	{
		_prop = new Properties();
        String res = "";
		_loadedExtensions = new ConcurrentHashMap<String, Object>();
		try
		{
			_prop.load(new FileInputStream(CONFIG));
        } 
		catch (FileNotFoundException ex) 
        {
            _log.info(ex.getMessage() + ": no extensions to load");
		}
		catch (Exception ex) 
		{
			_log.log(Level.WARNING, "could not load properties", ex);
		}
		_classLoader = new JarClassLoader();
		for (Object o : _prop.keySet()) 
		{
			String k = (String)o;
			if (k.endsWith("Class")) 
			{
				res += initExtension(_prop.getProperty(k)) + "\n";
			}
		}
        return res;
	}

    /**
     * init a named extension
     * @param name the class name and optionally a jar file name delimited with a '@' if the jar file is not
     * in the class path
     */
    public String initExtension(String name) 
    {
        String className = name;
        String[] p = name.split("@");
        String res = name + " loaded";
        if (p.length > 1) 
        {
            _classLoader.addJarFile(p[1]);
            className = p[0];
        }
        if (_loadedExtensions.containsKey(className))
            return "already loaded";
        try 
        {
            Class<?> extension = Class.forName(className, true, _classLoader);
            Object obj = extension.newInstance();
            extension.getMethod("init", new Class[0]).invoke(obj, new Object[0]);
            _log.info("Extension " + className + " loaded.");
            _loadedExtensions.put(className, obj);
        } 
        catch (Exception ex) 
        {
            _log.log(Level.WARNING, name, ex);
            res = ex.toString();
        }
        return res;
    }

	/**
	 * create a new class loader which resets the cache (jar files and loaded classes)
	 * on next class loading request it will read the jar again
	 */
	protected void clearCache() 
	{
		_classLoader = new JarClassLoader();
	}

	/**
	 * call unloadExtension() for all known extensions
	 *
	 */
	public String unloadExtensions() 
	{
        String res = "";
		for (String e : _loadedExtensions.keySet())
			res += unloadExtension(e) + "\n";
        return res;
	}

    /**
     * get all loaded extensions
     * @return a String array with the class names
     */
    public String[] getExtensions() 
    {
        String[] l = new String[_loadedExtensions.size()];
        _loadedExtensions.keySet().toArray(l);
        return l;
    }

    /**
     * unload a named extension
     * @param name the class name and optionally a jar file name delimited with a '@'
     */
    public String unloadExtension(String name) 
    {
        String className = name;
        String[] p = name.split("@");
        if (p.length > 1) 
        {
            _classLoader.addJarFile(p[1]);
            className = p[0];
        }
        String res = className + " unloaded";
        try 
        {
            Object obj = _loadedExtensions.get(className);
            Class<?> extension = obj.getClass();
            _loadedExtensions.remove(className);
            extension.getMethod("unload", new Class[0]).invoke(obj, new Object[0]);
            _log.info("Extension " + className + " unloaded.");
        } 
        catch (Exception ex) 
        {
            _log.log(Level.WARNING, "could not unload " + className, ex);
            res = ex.toString();
        }
        return res;
    }

	/**
	 * unloads all extensions, resets the cache and initializes all configured extensions
	 *
	 */
	public void reload() 
	{
		unloadExtensions();
		clearCache();
		initExtensions();
	}

	/**
	 * unloads a named extension, resets the cache and initializes the extension
	 * @param name the class name and optionally a jar file name delimited with a '@' if the jar file is not
	 * in the class path
	 */
	public void reload(String name) 
	{
		unloadExtension(name);
		clearCache();
		initExtension(name);
	}

    /**
     * register a getter function given a (hopefully) unique name
     * @param name the name of the function
     * @param function the ExtensionFunction implementation
     */
	public void addGetter(String name, ExtensionFunction function) 
	{
	    _getters.put(name, function);
	}

    /**
     * deregister a getter function
     * @param name the name used for registering
     */
    public void removeGetter(String name)
    {
        _getters.remove(name);
    }

    /**
     * call a getter function registered with DynamicExtension
     * @param name the function name
     * @param arg a function argument
     * @return an object from the extension
     */
    public Object get(String name, String arg) 
    {
        ExtensionFunction func = _getters.get(name);
        if (func != null)
            return func.get(arg);
        return "<none>";
    }

    /**
     * register a setter function given a (hopefully) unique name
     * @param name the name of the function
     * @param function the ExtensionFunction implementation
     */
    public void addSetter(String name, ExtensionFunction function) 
    {
        _setters.put(name, function);
    }

    /**
     * deregister a setter function
     * @param name the name used for registering
     */
    public void removeSetter(String name) 
    {
        _setters.remove(name);
    }

    /**
     * call a setter function registered with DynamicExtension
     * @param name the function name
     * @param arg a function argument
     * @param obj an object to set
     */
    public void set(String name, String arg, Object obj)
    {
        ExtensionFunction func = _setters.get(name);
        if (func != null)
            func.set(arg, obj);
    }

    public JarClassLoader getClassLoader()
    {
        return _classLoader;
    }
}
